Blast Design Fly-rock

Works out the zones that flying rock can reach round a blast block, shows them over the model while you try values, builds them as polylines on request and opens a printable sheet with the values, the result and a plan. Press F1 over the ribbon button or in the window to open this guide.

Flyrock Zones

Opens a form with the hole, its charge, the rock and the factors of safety of the selected blast block, and works out two danger zones: one for people and one for equipment. The result is calculated again as you type, and the zones are drawn over the model while the form is open. Nothing is added to the project until you click Build zones.

Three calculation methods are offered:

McKenzie (ISEE) - the model of DataBlast and SHOTPlus: the longest throw from the hole diameter and the scaled depth of burial of the charge; the zone is that distance times the factor of safety.
Safety rules of the CIS: the distance from how full the hole is with explosive and stemming, the rock hardness and the hole size; the zone is rounded up to 50 m and is never under 200 m.
Lundborg - the upper bound: the longest throw from the hole diameter alone, an upper bound that is rarely reached; the zone is that distance times the factor of safety.

Where to find it

Blast Design tab → Calculation group → Flyrock Zones. The same button is on the Blast block tab, in the Calculation group.

The window does not block the program. Running the command again only brings the open window forward.

Before you start

Select one blast block with holes. Otherwise a message says "Select one blast block with holes first."
For a good start, charge the holes (Charge Holes) and give the block its rock. The form takes the following from the block:
- the widest hole, the longest charged length, the fullest charge, the least stemming;
- the density of the block's explosive from the explosive table (0.85 t/m³ if it is not there);
- the hardest rock of the block (0 if no rock is known), and the smaller of the burden and the spacing;
- the block's throw direction.
If the holes are not charged, the usual charge is taken (the hole less the usual stemming) and the hint line says "The holes are not charged: the usual charge is taken - the hole less the usual stemming."

How to

Select the block and click Flyrock Zones. The Fly-rock zones window opens.
Choose the Calculation method. Only the fields the method needs are shown in the last row of section 1.
Check or change the hole and charge values (section 1) and the factors and zone shape (section 2). The result in section 3 and the zones in the 3D view follow each change.
Click Build zones to draw the zones as polylines in the model, or Open in FastReport to get the sheet. Click Close when you are done; the sketch disappears with the window.

The method and the factors of safety are remembered between sessions. What comes from the block (hole, charge, rock, throw) is not: it is always taken from the block when the window opens.

Parameters

1 Hole and charge

Field	Unit	Meaning
Calculation method		McKenzie, Safety rules of the CIS or Lundborg. The tip on the list says what the method works from.
Hole diameter	mm	The widest hole of the block.
Hole length	m	The length the holes are charged over: the longest of the block.
Charge length	m	All the explosive of the hole, decks and all: the fullest charge of the block.
Stemming	m	The stemming above the charge: the least of the block.
Rock hardness f		Shown for the Safety rules only. Hardness on the Protodyakonov scale: the hardest rock of the block.
Hole spacing	m	Safety rules only. The smaller of the burden and the spacing of the holes.
Explosive density	t/m³	McKenzie only. Gives the mass of the charge.
Charge as one	diameters	McKenzie only. A long charge acts as a concentrated one over its top part: how many hole diameters of it are taken for the scaled depth of burial. Default 10.
Constant of Lundborg		Lundborg only. 260 is rock thrown without any confinement, the upper bound; it goes down to about 40 under an extreme confinement. Default 260.

No field accepts a negative number: such a field is marked red and the hint line says "A value is not right - see the field marked red." While any field is wrong, Build zones and Open in FastReport are off.

2 Safety and shape

Field	Meaning	Default
For people	Factor of safety, times the longest throw. DataBlast takes 2.	2
For equipment	Factor of safety for machines and buildings, which a fragment harms at the reach of the throw itself.	1
Throw	Which way the rock is thrown across the rows: None - a round zone, Towards the first row, Towards the last row. With a throw, the zones are longer ahead of the block than behind it.	The block's own
Ahead / aside / behind	Shown when there is a throw. The share of the distance the zone reaches along the throw, square to it and against it, in per cent.	100 / 75 / 50

3 Result

Shown in two columns. For McKenzie it contains the longest throw of a fragment, the explosive taken into account (kg), the depth of burial of the charge's centre and the scaled depth of burial (m/kg^(1/3)); for every method, the zone dangerous for people and the zone dangerous for equipment (m); with a throw, also the people's zone ahead / aside / behind. If the values do not allow a calculation the longest throw shows "—".

Warnings appear under the result:

Warning	What to do
The hole diameter is not given.	Enter the diameter.
The rock's hardness is not given: the rules cannot work out the fly-rock zone.	Enter the hardness or choose another method.
The hole spacing is not given: the rules cannot work out the fly-rock zone.	Enter the spacing.
The hole has no length, or the charge is longer than the hole.	Fix the hole length or the charge length.
The charge has no length or no density: McKenzie's model has nothing to bury.	Enter the charge length and the density.
The scaled depth of burial is under 1 m/kg^(1/3): the stemming is short for this charge, so cratering and long throws are likely. Take the figure as a guide only.	Lengthen the stemming or shorten the charge.
McKenzie's range came to more than Lundborg's upper bound; the bound is taken.	Nothing; the result is capped.

The buttons

Button	What it does
From the block	Fills the hole, the charge and the rock again from the block (the widest hole, the fullest charge, the least stemming, the hardest rock). The method and the factors stay.
Open in FastReport	Opens the sheet with the values, the result and the plan in FastReport Designer, where you can look at it, change its layout and print. The plan is drawn over a picture of the model seen from above when one can be taken; otherwise over the block alone.
Build zones	Draws the two zones as closed polylines in the active layer, at the collars' elevation, as one undo step (`Ctrl`+`Z`), each in its own colour. The hint line says "Built N polylines in the layer "name"." Off when there is no zone.
Close	Closes the window and removes the sketch.

How the zones are shaped

Without a throw, each zone is the outline of the block (contour and collars) pushed outwards by the zone's distance. With a throw, the zone is longer along the throw direction by the shares set above. The zones are drawn at the average elevation of the collars, and an arrow shows the throw direction.

Reading the figures

The printed sheet repeats the formula of the method used and states that nobody and nothing that is not protected stays inside the zone for people when the blast is fired. The zones are measured from the block's outline and its holes.

If something goes wrong

Message	What to do
Select one blast block with holes first.	Select one block that has holes and run the command again.
A value is not right - see the field marked red.	Correct the red field (no negative numbers).
There is no zone to build.	The values give no zone; see the warnings under the result.
Could not make the fly-rock sheet: …	The report template could not be read or FastReport Designer is not installed.

What next

Charge Holes to change the charge and calculate again · Design Block